Propeller pitch control



April 17, 1951 E, MARTW 2,549,l08'

PROPELLER PITCH CONTROL Filed Dec. 29, 1943 April 17, 1951 E, MART|N- 2',549,108l

PROPELLER PITCH CONTROL Filed Dec. 29, 1943 2 Sheets-Sheet 2 w INVENTOR E're Maz'in eflzzqzwey Patented Apr. 17, 1951 UNITED STATES PATENT OFFICE PROPELLERPITCH CONTROL Erle Martin, West Hartford, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application December 29, 1943, Serial No. 516,042

This application is a continuation-in-part of U. S. application Serial No. 460,495, filed October 2, 1942, by Erle Martin, now abandoned.

This invention relates to improvements in speed control apparatus for aircraft power plants with particular reference to a power plant which includes two engines and two controllable-pitch propellers.

An object of the invention resides in the provision of a control apparatus of the Character indicated which uses only a single governor driven by one of the engines.

A further object resides in the provision of a power plant speed control apparatus whichis operative to maintain both engines at a speed determined by the setting of the governor by controlling the pitch of the engine driven propellers.

A further object resides in the provision of means to proportion the total thrust between two mechanically connected propellers.

A still further object resides in the provision of alspeed control apparatus of the Character indicated which includes manually adjustable means for varying the speed or thrust of one propeller with respect to the speed or thrust of the other in order that slight variations in the speed or thrust may be corrected, or the two propellers 14 Claims. (Cl. PJO-435.24)

may be caused to operate at slightly'difierent speeds or with slightly different thrusts if such a method of operation should be desired, as, for instance, in order to control the direction of the aircraft.

An additional object resides in the provision of speed controlling apparatus of simplified construction, involving economy of parts with consequent reduction in weight and in the possibility of mechanical failure.

` Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompany drawings, in which like reference numerals are used to designate similar parts throughout, there is illustrated a suitable mechanical embodiment for the purpose of disclosing the invention.

In the drawings, Fig. 1 is a somewhat diagrammatic rear elevational view of the propeller hub portions of two engines, showing the application thereto of apparatus constructed according to the invention. w i

Fig. 2 is a diagrammatic illustrationiof a portion of the speed control apparatus of one of the engines.

Fig. 3 is a schematic view showing independent power units, and i Fig. 4 is a schematic view showing engines and propeller. geared together.

Referring to the drawings in detail, the numeral Hi generally designates the hub portion of one propeller andV IZ designates the hub portion of a' second propeller, the two propellers with their engines constituting the main component of the power plant. The two propellers may be geared' together to rotate in opposite directions, and therefore having opposite pitches, with each engine A andB supplying powerto both propellers through the interconnecting gear train :as shown in the Zimmerman Pat. No. 2,431,293, issued November 18, 1947 and as schematically shown in Fig. 4 of this application or eachpropeller may be 'separately driven by its respective engine so' that each engine-propeller unit is an independent' unit as shown in Fig. 3. Each p-ropeller hub carries a plurality of blades rotatably mounted forA pitch changing movements, one of the blades for the hub li] being indicated at |4 land one of the blades for hub IZ being indicated at Hi.

The manner in which the blades are moved for pitch adjustment is diagrammatically illustrated in Fig. 2. In this figure the propeller is shown as having three blades, indicated at IS, 18, and 20,`

and is supported and driven byan engine 22. Within the shank or root portion' of each blade there it a vane type hydraulic motor, Vzone of which is shown in section in Fig. 2. This motor has a relatively fixed inner member 24 to which` are secured a pair of diametrically opposed abutments 26 and 28 and the propeller blade has a pair of diametrically opposed vanes 30 and 32 which cooperate with the inner abutments to provide segmental shaped expansion chambe'rs in the`` motor. Fluid under pressure is supplied by a pump 34, which may comprise an annular Series of cylinders, as indicated at 36 and .38, carried by the propeller hub for rotation therewith and eazh'V including a piston, as' indicated at Ali] and 42, respectively, which pistons have portions contacting a fixed cam 44 which is eccentric to the axis of rotation of the propeller so that the pump pistons will be reciprocated in their cylinders as they are rotated with the propeller about the cam. An.

annular sump 46 is carried by the pump casing and connected With the intake of the pump cylinders and a pressure fluid manifold 48'is also carried by the pump casing and connected with the outlet of the pump cylinders. The usual relief valve 49 is provided between the pump inlet and outlet. i

AdiStributing Valve 5B is carried byV the propeller `and hydraulically interposed between the against rotation by slidable keys; member is supportedby integral arms ||'8 slid- 3 pump 34 and the vane motors of the propeller. The pressure manifold '43 of the pump is connected vwith this valve at port 52, while the sump 46 is connected with the valve through the drain connections 54 and 56. The opposite sides of the pitch changing motors are connected with the valve through channels 58 and 69 and the valve contains a plunger 62 provided with pistons 64 and 166 which control the connections between port 52 and channels 58 and 69 and also between the channels and the drain connections 54 and 567m a mannerto supply fluid under pressure to one side or the other of the motor while connecting the opposite side with drain, in response to a movement of plunger '62 in one direction, and to reverse these connections upon a movement of plunger 62 in the opposite direction. i The Valve cylinder is in the form of a sleeve ,68 surrounding plunger 62 and slidable in Valve body by mechansm comprising cam 19 on the motor, lever 12 mounted on a fulcrum 14 and having one end in contact with cam 19, the other end of theV level' being pivotally connectedV to sleeve 58. A compression spring 16 maintains the free end of the lever in contact with cam 10. This follow-up mechansm acts to maintain the' propeller pitch i at an angle corresponding to the particular position of 'plunger 52. The free end of plunger B2 rack 84. When rack 84 is moved lengthwise it irotatres gear 82 within fixed cylinder 83 which supports cam 44.

inder 88 'and is integral with gear 82, therefore, rotation of gear B2 causes disc 18 to move length- Spline '80 spirally engages. cylwise thereby imparting longitudinal movement to plunger'62. i v T Rack 84 is connected with rack 94 of the other propeller by a pair of axially aligned links, in the form of rods 96 and 98, which are inter-connected Vby ;a manually operable adjusting mechansm generally indicated at *I 00. Rack 84 is movable by a servo-motor 99 A(Figfl) controlled in' known manner by a speedgovernor generally indicated at 92. i

Motorflfl includes a piston |702 connected ,with

rack'8'4 and rod 96 and reciprocable in cylinder |ll4.. Fluid under pressure is supplied between the 'piston and the cylinder head m6 through a channel leading from the governor 92 'and includi ing the port lfl'l. This governor Controlled supply of fluid under pressure serves to move the piston |92 in one direction. The piston is moved in the opposite direction by compression Springs m8 en- :closed in a. casing I Ill and bearing 'at one end against a fixed abutment I |2 and at the other end against a movable abutment I |4 connected with' rod 98V and rack 94. The hydraulic portion of the servo-motor and the'spring portion tbereof being connected respectively with racks 84 and 94 serve to maintain rods 96 and 98 in tension, and the rods 4may,therefore, be relatively light in'weight.

The manual'adjustment IOB comprises 'a'tubu-.

lar member I |6 into which the adjacent endsof rods 96 andV 98 extend and in which they are held This tubular ably -mounted on a pin 129 in bracket |22 secured 1 to a relatively fixed part of the airplane, preferably midway between the propellers. Rods 96 position by sheaves |24 and |26, set snugly into slots in member |6 and threaded onto the ends i has'a head 63 in an annulus in disc 18 which is i movable axially by a spiral spline 'B0 integral with the external gear 182, which is rotatable'by 4 of the rods. Either or both of the sheaves may be rotated manually by cables I 28, |30.

Rotation of the sheaves about the screw threads on the rods 'will cause the rods to move axially into or out of the sheaves and will thus move one or both of the rack's 84 and 94, depending upon the condition of the hydraulic portion of the servo-motor 90. Normally, rack l84 will be positioned entirely by the servo-motor and only rack 94 will be moved by 'adjustment of the sheaves. The normal use of the manual adjustment |09 is to change the pitch of one of the propellers a slight amount to compensate for changes or irregularities in the inter-connecting mechansm such as might be caused by temperature changes or other conditions or to equalize or contro1 propeller Operating characteristics such as thrust or speed. The main speed adjustment of the power plant is the speed setting adjustment of the governor 92 which may include a governor carried sheave |32 manually rotatable by cable |34Vleading over idler sheaves |39 to a lo'-` cation convenient for the pilot.

In the construction of Fig. 4, in which the propellers are geared together, a change in the governor` setting by movement of sheave |32 or a change in the throttle openingof either or both engines, which will cause a change in speed suflicient to operate the governor to restore the speed, will cause a simultaneous and equal change in the pitch of both propellers to maintain the speed of both propellers at the speed determinedj by the governor setting. Both propellers will operate at the same speed because they are geared together. A change in the pitch of the blades of one propeller without a corresponding change in the pitch of the blades of the other propeller by movement of sheave 12-4 or 126 will cause the-governor to act if the propeller speed is affected to 'compensate for any change in the speed of the propellers, which are maintained at' power delivered to both propellers which will remain unchanged. The propellers will then act in a manner similar to a rudder 'and cause the airplane to turn.

In the construction shown in Fig. 3, in which the engines and propeller .are separate units, as-

suming both engines A and B to be running at.

the same speed, a change in the governor setting by movement of sheave [32 will cause a simultaneous and equal change of the pitch of both propellers to maintain the speed of both propellers substantially the same as the speed determined by the governor setting. An independent change of the throttle opening of either engine' or an independent change of the pitch of either propeller will cause achange in the relative speeds of the engines.

There has thus been illustrated and described 'a suitable control for two or more jointly operating enginesv, utilizing a single governor and a single governor-Controlled servo-motor connected by linkage with two propellers and in which a manual device is provided for adjusting the 1ink'-" age inter-connecting the two propellers for temperature change, expansion and contraction, and;

also to provide a manual control of one or both of the propellers iif de'sired.

It Yis to `be understood that the 'invention :is not limited to the 'specific embodiment herein illustrated and described, but 'may be used 'in -other ways without departure from its spirit as defined by the following claims. i

I claim:

1. In an aircraft 'powerplant including 'a't .least 'two engnes and an adjustable pitch propeller driven by each engine, means for substantially synchronizing the speeds of said engines, said synchronizing means including pitch-'adju'sti'ng means for each propeller, in combination with la governor driven by one of said engines, and servo mechanism operatively connecting said governor with each of said pitch-adjusting means, said servo 'mechanism including manual'ly adjustable means for providing limited speed variations between said engines while both propellers are under control of said governor.

2. 'I'he invention set forth in claim 1 in which said servo device is hydraulically operated.

3. In a powerplant including at least two engihes in yspaced-apart relation on Aan aircraft, each engine driving a controllable-pitch propeller, speed regulating means for said engines, comprising in combination, a pitch changing mechanism for 'each propeller, each pitch changing mechanism including an axially movable rack, linkage 'interconnecting said 'racks, a governor driven by one of 'said engines, a single actin'g hydranlic motor actuated by said governor and Zoperatively connected with one of said racks to urge it in a direction away from the other of said racks, and a compression spring operatively associated with said other rack to .resiliently urge said other rack away from said first rack, thereby maintaining said linkage under tension.

`v4. The arrangement set forth in claim 3 including manually operable means for varying the length of said linkage.

.5. Control apparatus for anv aircraft powerplant comprising at least two engines each en- 4.

gine driving its own separate controllable-pitch propeller, in combination with a speed responsive governor for directly controllingthe pitch of one ofisaid propellers and having a connection with the other propeller for simultaneously controlling the pitch of said other propeller, and means for manually controlling the pitch of said other propeller with respect to said one propeller while both propellers are under control of said governor.

6.111 an airplane, two spaced-apart enginedriven controllable-pitch propellers each `having pitch changing mechanism, a speed governor driven in timed relation with one of said propellers and governing the speed of said one propeller by controlling the pitch thereof, means for extending the control of said governor to the other propeller and changing the pitch of the other propeller simultaneously with, and substantially the same amount as, the pitch change in said one' propeller including linkage interconnecting the pitch changing mechanism of said two propellers, a servomotor operatively connected with said governor and saidlnkage vadjacent one end of said linkage for Operating the pitch changing mechanism of said Vone propeller and moving said linkage in one direction, a spring adjacent the pitch changing mechanism of said other propeller and Operating on said linkage adjacent the otherv end of said "linka'ge for moving f'said llm'ka'ge in the other direction and ;maintaining said `1ir1l .'age continuously 'blased lin one direction, meansa'ssociated with the pitch changing 'mechanism of said other propeller Ifor 'trainslating` movements of said iinkage into pitch changing -mov'ements of said other propeller and means for changing the pitch 'of said other propeller with respect to the pitch 'of 'said one 'propeller while maintaining 'governorl control of 'both propellers comprising means 'forming a portion of said linkage between said servomotor and said spring for altering 'the length of said linkage. i

7. Control means 'for two engine-driven controllable-p'itch propellers, comprising in `vcombination, pitch varying mechanism 'for each propeller., means, including link'age, interconnecting the pitch varying mechanism` of said prop'ellers,`

'a 'govern'or driven Vin timed relation with one of said propellers, an hydraulic cylinder servo device arranged at one end of said linkage and interconnecting said 'governor 'and said mechanism of said one propeller, and a spring at the i other end 'of said linkage maintaining said linkage under tension.

8. In combination with two controllable-pitch propellers each having hydraulically actuated pitch changing mechanism, a two-part valve in each propeller one part of which is positioned by the 'propeller blades and movable by the pitch changing movemen'ts of said blades,` the position of the 'second part of 'said valve determining the propeller pitch, a governor driven in timed relation with one propeller and controlling the position of the Second part of the valve associated 'with 'said one propeller for mainta-ining 'the speed of said one propeller at a. predetermined value by controlling the pitch thereof, means connecting the second valve part of one propeller with the second 'valve part of the other propeller for causing substant'i'ally simultaneous and equal pitch changes in` the two .propellers and `means for varying the pitch of one propeller with respect to the other propeller.

9. In combination with two cohtrollable-pitch pronellers each having hydraulically actuated pitch changing mechanism, a two-part valve in each propeller one part of each valvebeing positioned by the propeller blades of its respective propeller and movable by the pitch changing move'ments of said blades, the position of the second part of each valve determining the pitch of its respective propeller, a governor driven in timed relation with'one propeller and controlling the position of the second part of theivalve associated with said one propeller for 'mainta'ining the speed of 'said one propeller at a predejtermined Value by controlling the pitch thereof, means connecting the second valve part of said one propeller with the second valve nart of the other propeller for causing substantially simultaneous and eoual pitch changes in the twopropellers, and means for varving the pitch of one propeller with respect to the other propeller including means for adjusting the connection between the second valve parts of the two propellers while both propellers are rotating.

10. In an aircraft, two spaced-apa-rt enginedriven controllable pitch propellers operatively connected togetherv for simultaneous rotation, means for changing the pitch of eachpropeller. a speed governor driven in timed relation with one of said propellers and controlling the pitch thereof, means for extending the control of said governor tov the other propeller and changing the pitch of the other propellerv simultaneously with, and substantially the same amount as, the

pitch change in said one propeller, including linkage interconnecting the pitch changing mechanism of said two propellers, a. servo-motor operatively connected with said governor and said linkage adjacent one end of said linkage for 'operating the pitch changing mechanism of 'changing mechanism of said other propeller and Operating on said linkageadjacent the other end of said linkage for moving said linkage in the other direction and maintaining said linkage under tension, means forming a portion of said linkage associated with the pitch changing mechanism of said other propeller for translating movement of said linkage into pitch changing movernents ofsaid other propeller and means for changing the pitch of said other propeller With respect to the pitch of said one propeller while maintaining governor control of both propellers comprising means between said servomotor and said spring for altering the length of said linkage.

11. In a power plant including at least two engine-driven controllable-pitch propellers in spaced-apart relation on an aircraft, and operatively connected together for simultaneous rotation, speed regulating means for said propellers comprising in combination, a pitch changing mechanism including an axially movable rack, for each propeller, linkage interconnecting said racks, a governor driven in timed relation with one of said propellers, a single actinghydraulic motor actuated by said governor and operatively connected' with one of said racks to urge it in a direction away from the other of said racks, and a spring o-peratively associated With said 'other rack to resiliently urge said other rack away from the said first rack, thereby maintaining said linkage underltension. j 12.1` The arrangement set forth in claim 11 ini cluding manually operable means for -varyingthe length of said linkage.

13. Speed regulating means for at least two engines on an aircraft, each engine driving a respective variable pitch .propeller having pitch varying. mechanism effective for controlling the load on the engine to which it is connected and having separate sources of power for `Operating the respective pitch varying mechansrn, comprising inV combination, means interconnecting a portion of the pitch varying mechanism of one vof said propellers andla similar portion of the pitch varying mechanism of-the other of said propellers for simultaneously actuating both of said pitch varyingmeehanisms, a governor driven by one of said mechanisms and a servo deviceintercon- Number Name Date 754,038 Ball et al. Mar..8', 1904 1,421,803 Martin July 4, 1922 2,023,'785 Hoover Dec. 10, 1935 2,112,955 Koster Apr. 5, 1938 2123,05? Martin July 5, 1938 2125474 Wachs Aug. 2, 1938 2205525 Mader 'June 25, 1940 2,224,177 Algarsson Dec. 10, 1940 2,229,058 Dicks Jan, 21, 1941 2,236,841 Waseige Apr. 1,1941 2,250,695 Algarsson July 29, 1941' l`2251126 'Rindfieisch Sept. 30,` 1941 'i 2,28o,654 Mader zip-n21, 1942 2,284,473 Menasoo et al. Mayl 26,1942V 2302,042 Martin Nov. 17', 1942 2,312,62 4 I Caldwell Mar.. 2, 1943 2,319,218 Drake May 18, 1943 '2324,625 Hoover July 20, 1943 2,325,632 w Pullinv Aug. 3, 1943 2,354,422 Roby Ju1y 25,1944 2,362,444` Blanchard et al. 'Nov..14, 1944 A2,3'70,149 Couch Feb. 27, 1945 2,380,889 Waseige July 31, 1945 v424143766l Platt Jan. 21, 1947 FOREIGN PATENTS Number i Country Date 134,259v Great Britain.V Oct. 30, 1919 necting said governor and'said portionv of ,one of said'mechanisms; said interconnecing means including linkage and means for maintaim'ng said linkage under tension, said servo device being operable by a hydraulic cylinder at one end of said linkage, said means for maintaining said linkage under tension comprising a spring at the other end of said linkage.

. i 14. Speed regulating means for at least two engines on an aircraft, comprising in combinadon', a variable pitch propeller driven by ;each engine, and effective for controlling the load on theengine to which it is connected, separate pitch varyingmechanism for each propeller, means including linkagel interconnecting the pitch varying mechanisms of said propellers, a governor driven by` one of said engines and a servo-device including a hydraulic cylinder at one end of said linkage interconnecting said governor and saidv mechanism and-a spring at the other end of said linkage for mantaining said linkage under tension.

' i v i ERLE MARTIN.

REFRENCES CITED UNITED S TAVTES PATENTS 503,154 Great Britain Apr. 3, 1939 

